Calorie Deficit Calculator

A calorie deficit occurs when you consume fewer calories than your body burns in a day. Your body makes up the difference by drawing on stored energy — primarily body fat. A deficit of 500 kcal/day leads to roughly 0.5 kg of fat loss per week.

Use a TDEE calculator to find your total daily calorie burn. TDEE combines your BMR (calories burned at rest) with your activity level. Enter that TDEE number into this calculator to get your daily deficit target.

Yes — a 500 kcal/day deficit is the most commonly recommended level for sustainable fat loss. It produces approximately 0.5 kg of fat loss per week, which is fast enough to see results while being moderate enough to preserve muscle mass, hormones, and energy levels. Deficits over 1,000 kcal/day are generally considered aggressive and risk muscle loss.

To lose 1 kg of fat per week, you need a weekly deficit of 7,700 kcal — or 1,100 kcal/day below your TDEE. This is considered an aggressive cut and requires high protein intake (2+ g/kg body weight) to minimise muscle loss. It is generally only appropriate for people with significant excess body fat or under medical supervision.

Most guidelines set the floor at 1,200 kcal/day for women and 1,500 kcal/day for men. Going below these levels makes it very difficult to meet micronutrient needs and risks metabolic adaptation, hormonal disruption, and muscle loss. If your TDEE deficit calculation produces a target below these thresholds, reduce the rate of loss instead.

A deficit alone does not necessarily cause muscle loss. Adequate protein intake (1.6–2.2 g per kg of body weight) and resistance training 3–4 days per week preserve or even increase muscle during a cut. The most common cause of muscle loss is eating too little protein, not the deficit itself.

At a standard rate of 0.5 kg/week, losing 10 kg takes approximately 20 weeks (about 5 months). At a faster rate of 1.0 kg/week, it takes ~10 weeks, but this requires a 1,100 kcal/day deficit and substantially higher protein. Enter your current and goal weights above and the calculator estimates your timeline automatically.

It depends on how you calculated your TDEE. If your TDEE already includes your exercise (e.g., you selected 'moderately active'), then eating back workout calories would erase your deficit. If you used a sedentary TDEE and added workouts separately, eating back 50–75% of the estimated burn helps avoid too large a deficit on training days.

Prolonged severe deficits can reduce metabolic rate through adaptive thermogenesis — the body burns fewer calories in response to sustained restriction. Keeping your deficit moderate (300–600 kcal/day), maintaining protein intake, and including resistance training minimises this effect. Taking a 1–2 week diet break at maintenance every 8–12 weeks can partially restore metabolic rate.

The deficit determines your total calorie target. Your macro calculator then splits those calories into protein, carbohydrates, and fat. Protein is set first (1.6–2.2 g/kg) to protect muscle, then the remaining calories are split between carbs and fat based on preference and training demands.

Most fitness professionals recommend cutting when body fat is above 15–20% for men or 23–28% for women. Cutting at very low body fat is harder to sustain and risks muscle loss. If you're unsure of your body fat, use a body fat calculator first, then plan your deficit from there.

Technically yes, but it's difficult in practice. Exercise burns 200–600 kcal per session for most people — much less than commonly assumed. Creating a 500 kcal daily deficit through exercise alone would require roughly 60–90 minutes of moderate-intensity cardio every day. Most people find a combination of moderate dietary restriction and 3–4 exercise sessions per week far more sustainable.